Refactor get/set_property to take the item as first argument

lily/tuplet-iterator.cc

 /*
   This file is part of LilyPond, the GNU music typesetter.
 
   Copyright (C) 1998--2020 Han-Wen Nienhuys <hanwen@xs4all.nl>,
                  Erik Sandberg <mandolaerik@gmail.com>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
@@ skipping 54 matching lines @@
 {
   SCM ev_scm = Lily::make_span_event (ly_symbol2scm ("TupletSpanEvent"),
                                       scm_from_int (d));
 
   Music *mus = get_music ();
 
   Music *ev = unsmob<Music> (ev_scm);
   ev->set_spot (*mus->origin ());
   if (d == START)
     {
-      ev->set_property ("numerator", mus->get_property ("numerator"));
-      ev->set_property ("denominator", mus->get_property ("denominator"));
-      ev->set_property ("tweaks", mus->get_property ("tweaks"));
-      ev->set_property ("length", spanner_duration_.smobbed_copy ());
+      set_property (ev, "numerator", get_property (mus, "numerator"));
+      set_property (ev, "denominator", get_property (mus, "denominator"));
+      set_property (ev, "tweaks", get_property (mus, "tweaks"));
+      set_property (ev, "length", spanner_duration_.smobbed_copy ());
     }
 
   synthesized_events_ = scm_cons (ev_scm, synthesized_events_);
   return ev;
 }
 
 Tuplet_iterator::Tuplet_iterator ()
 {
   spanner_duration_ = next_split_mom_ = 0;
   synthesized_events_ = SCM_EOL;
@@ skipping 32 matching lines @@
     }
   Music_wrapper_iterator::process (m);
   if (child_iter_ && child_iter_->ok ())
     descend_to_child (child_iter_->get_outlet ());
 
 }
 
 void
 Tuplet_iterator::construct_children ()
 {
-  if (Duration *d = unsmob<Duration> (get_music ()->get_property ("duration")))
+  if (Duration *d = unsmob<Duration> (get_property (get_music (), "duration")))
     spanner_duration_ = d->get_length ();
   else if (Moment * mp
-           = unsmob<Moment> (get_outlet ()->get_property ("tupletSpannerDuration")))
+           = unsmob<Moment> (get_property (get_outlet (), "tupletSpannerDuration")))
     spanner_duration_ = mp->main_part_;
   else
     spanner_duration_.set_infinite (1);
 
   Music_wrapper_iterator::construct_children ();
 
   if (child_iter_ && child_iter_->ok ())
     descend_to_child (child_iter_->get_outlet ());
 }
 
 void
 Tuplet_iterator::derived_mark () const
 {
   scm_gc_mark (synthesized_events_);
   Music_wrapper_iterator::derived_mark ();
 }
 
 IMPLEMENT_CTOR_CALLBACK (Tuplet_iterator);